1. Field of the Invention
This invention relates to tunable, variable or adjustable capacitors and is directed particularly to improvements in the structure of tunable capacitors whereby the capacitor is fully sealed against the penetration of gases, dust or other contaminants and yet is tunable over its entire range from the exterior of its package without breaking or otherwise impairing the effectiveness of the seal.
2. Description of the Prior Art
This invention is primarily an improvement of the structure or housing of the variable disc capacitor taught by U.S. Pat. No. 3,701,932 issued in the same inventor. It also relates in general to U.S. Pat. No. 4,095,263 issued to the same inventor.
In the present invention, the capacitor of U.S. Pat. No. 3,701,932 has been miniaturized and redesigned in its structure to fit into a sealed housing. It shares many of the design improvements of the capacitor disclosed in U.S. Pat. No. 4,095,263 except for the construction of the sealed housing.
The principle object of the present invention is to provide a miniature tunable or variable capacitor which is fully enclosed within a sealed housing such that air, gases, moisture, dust, or other contaminants cannot enter or penetrate the sealed package, while at the same time to provide a variable capacitor which is tunable over its entire range from outside the sealed package without breaking the seal or otherwise impairing its effectiveness.
A second object of this invention is to provide a compact, tunable capacitor which is stable in performance with respect to temperature changes, physical shock and other environmental factors.
Another object of this invention is to provide a miniature ceramic disc capacitor with these features which is easily tunable with a square tuning tool made of a dielectric material so as not to introduce strays into the circuit while tuning.